Enhanced Sensitivity for the Determination of Lithium by Miniaturized Liquid Cathode Glow Discharge (LCGD) Atomic Emission Spectrometry (AES) with the Addition of Surfactants

Abstract

A miniature atomic emission spectrometry (AES) was developed using a liquid cathode glow discharge (LCGD) as an excitation source and optical fiber spectrometer as the detection system. The instrument was employed for the sensitive determination of lithium (Li). The addition of 0.15% cetyltrimethylammonium chloride (CTAC), 0.15% cetyltrimethylammonium bromide (CTAB) and 3 critical micelle concentration (CMC) Triton X-405 enhanced the Li emission by 3.7-, 3.2-, and 1.8-fold, respectively. The presence of 50 mg L⁻¹ Al³⁺ and SO₄²⁻ inhibited the recovery of 0.5 mg L⁻¹ Li about 73% and 75%, respectively. After adding CTAB, CTAC, and Triton X-405, the recovery of Li was from 98% to 108%, suggesting that the addition of surfactant eliminated the Al³⁺ and SO₄²⁻ interferences. The sensitivity of Li was improved by adding the surfactants by factors of 2.3 for 0.15% CTAB, 2.0 for 0.15% CTAC, and 1.9 for 3 CMC Triton X-405. The limit of detection (LOD) with 0.15% CTAB for Li was 0.55 μg L⁻¹ which was improved by 5.6-fold. In addition, the energy consumption was below 60 W and good precision was obtained. The accuracy, reliability, and repeatability of the proposed method were verified by analysis of water samples and satisfactory recoveries between 91% and 115% were obtained. The results demonstrate that LCGD-AES with surfactants can be used for highly sensitive determination of Li in complex samples because of its low cost, small size, and low power consumption.